/******************************************************
Purge obsolete records

(c) 1997 Innobase Oy

Created 3/14/1997 Heikki Tuuri
*******************************************************/

#include "row0purge.h"

#ifdef UNIV_NONINL
#include "row0purge.ic"
#endif

#include "fsp0fsp.h"
#include "mach0data.h"
#include "trx0rseg.h"
#include "trx0trx.h"
#include "trx0roll.h"
#include "trx0undo.h"
#include "trx0purge.h"
#include "trx0rec.h"
#include "que0que.h"
#include "row0row.h"
#include "row0upd.h"
#include "row0vers.h"
#include "row0mysql.h"
#include "log0log.h"

/************************************************************************
Creates a purge node to a query graph. */

purge_node_t *row_purge_node_create(
    /*==================*/
    /* out, own: purge node */
    que_thr_t *parent, /* in: parent node, i.e., a thr node */
    mem_heap_t *heap)  /* in: memory heap where created */
{
  purge_node_t *node;

  ut_ad(parent && heap);

  node = mem_heap_alloc(heap, sizeof(purge_node_t));

  node->common.type = QUE_NODE_PURGE;
  node->common.parent = parent;

  node->heap = mem_heap_create(256);

  return (node);
}

/***************************************************************
Repositions the pcur in the purge node on the clustered index record,
if found. */
static ibool row_purge_reposition_pcur(
    /*======================*/
    /* out: TRUE if the record was found */
    ulint mode,         /* in: latching mode */
    purge_node_t *node, /* in: row purge node */
    mtr_t *mtr)         /* in: mtr */
{
  ibool found;

  if (node->found_clust)
  {
    found = btr_pcur_restore_position(mode, &(node->pcur), mtr);

    return (found);
  }

  found = row_search_on_row_ref(&(node->pcur), mode, node->table, node->ref, mtr);
  node->found_clust = found;

  if (found)
  {
    btr_pcur_store_position(&(node->pcur), mtr);
  }

  return (found);
}

/***************************************************************
Removes a delete marked clustered index record if possible. */
static ibool row_purge_remove_clust_if_poss_low(
    /*===============================*/
    /* out: TRUE if success, or if not found, or
    if modified after the delete marking */
    purge_node_t *node, /* in: row purge node */
    ulint mode)         /* in: BTR_MODIFY_LEAF or BTR_MODIFY_TREE */
{
  dict_index_t *index;
  btr_pcur_t *pcur;
  btr_cur_t *btr_cur;
  ibool success;
  ulint err;
  mtr_t mtr;
  rec_t *rec;
  mem_heap_t *heap = NULL;
  ulint offsets_[REC_OFFS_NORMAL_SIZE];
  *offsets_ = (sizeof offsets_) / sizeof *offsets_;

  index = dict_table_get_first_index(node->table);

  pcur = &(node->pcur);
  btr_cur = btr_pcur_get_btr_cur(pcur);

  mtr_start(&mtr);

  success = row_purge_reposition_pcur(mode, node, &mtr);

  if (!success)
  {
    /* The record is already removed */

    btr_pcur_commit_specify_mtr(pcur, &mtr);

    return (TRUE);
  }

  rec = btr_pcur_get_rec(pcur);

  if (0 !=
      ut_dulint_cmp(node->roll_ptr,
                    row_get_rec_roll_ptr(rec, index, rec_get_offsets(rec, index, offsets_, ULINT_UNDEFINED, &heap))))
  {
    if (UNIV_LIKELY_NULL(heap))
    {
      mem_heap_free(heap);
    }
    /* Someone else has modified the record later: do not remove */
    btr_pcur_commit_specify_mtr(pcur, &mtr);

    return (TRUE);
  }

  if (UNIV_LIKELY_NULL(heap))
  {
    mem_heap_free(heap);
  }

  if (mode == BTR_MODIFY_LEAF)
  {
    success = btr_cur_optimistic_delete(btr_cur, &mtr);
  }
  else
  {
    ut_ad(mode == BTR_MODIFY_TREE);
    btr_cur_pessimistic_delete(&err, FALSE, btr_cur, FALSE, &mtr);

    if (err == DB_SUCCESS)
    {
      success = TRUE;
    }
    else if (err == DB_OUT_OF_FILE_SPACE)
    {
      success = FALSE;
    }
    else
    {
      ut_error;
    }
  }

  btr_pcur_commit_specify_mtr(pcur, &mtr);

  return (success);
}

/***************************************************************
Removes a clustered index record if it has not been modified after the delete
marking. */
static void row_purge_remove_clust_if_poss(
    /*===========================*/
    purge_node_t *node) /* in: row purge node */
{
  ibool success;
  ulint n_tries = 0;

  /*	fputs("Purge: Removing clustered record\n", stderr); */

  success = row_purge_remove_clust_if_poss_low(node, BTR_MODIFY_LEAF);
  if (success)
  {
    return;
  }
retry:
  success = row_purge_remove_clust_if_poss_low(node, BTR_MODIFY_TREE);
  /* The delete operation may fail if we have little
  file space left: TODO: easiest to crash the database
  and restart with more file space */

  if (!success && n_tries < BTR_CUR_RETRY_DELETE_N_TIMES)
  {
    n_tries++;

    os_thread_sleep(BTR_CUR_RETRY_SLEEP_TIME);

    goto retry;
  }

  ut_a(success);
}

/***************************************************************
Removes a secondary index entry if possible. */
static ibool row_purge_remove_sec_if_poss_low(
    /*=============================*/
    /* out: TRUE if success or if not found */
    purge_node_t *node,  /* in: row purge node */
    dict_index_t *index, /* in: index */
    dtuple_t *entry,     /* in: index entry */
    ulint mode)          /* in: latch mode BTR_MODIFY_LEAF or
                         BTR_MODIFY_TREE */
{
  btr_pcur_t pcur;
  btr_cur_t *btr_cur;
  ibool success;
  ibool old_has = 0; /* remove warning */
  ibool found;
  ulint err;
  mtr_t mtr;
  mtr_t *mtr_vers;

  log_free_check();
  mtr_start(&mtr);

  found = row_search_index_entry(index, entry, mode, &pcur, &mtr);

  if (!found)
  {
    /* Not found */

    /* fputs("PURGE:........sec entry not found\n", stderr); */
    /* dtuple_print(entry); */

    btr_pcur_close(&pcur);
    mtr_commit(&mtr);

    return (TRUE);
  }

  btr_cur = btr_pcur_get_btr_cur(&pcur);

  /* We should remove the index record if no later version of the row,
  which cannot be purged yet, requires its existence. If some requires,
  we should do nothing. */

  mtr_vers = mem_alloc(sizeof(mtr_t));

  mtr_start(mtr_vers);

  success = row_purge_reposition_pcur(BTR_SEARCH_LEAF, node, mtr_vers);

  if (success)
  {
    old_has = row_vers_old_has_index_entry(TRUE, btr_pcur_get_rec(&(node->pcur)), mtr_vers, index, entry);
  }

  btr_pcur_commit_specify_mtr(&(node->pcur), mtr_vers);

  mem_free(mtr_vers);

  if (!success || !old_has)
  {
    /* Remove the index record */

    if (mode == BTR_MODIFY_LEAF)
    {
      success = btr_cur_optimistic_delete(btr_cur, &mtr);
    }
    else
    {
      ut_ad(mode == BTR_MODIFY_TREE);
      btr_cur_pessimistic_delete(&err, FALSE, btr_cur, FALSE, &mtr);
      if (err == DB_SUCCESS)
      {
        success = TRUE;
      }
      else if (err == DB_OUT_OF_FILE_SPACE)
      {
        success = FALSE;
      }
      else
      {
        ut_error;
      }
    }
  }

  btr_pcur_close(&pcur);
  mtr_commit(&mtr);

  return (success);
}

/***************************************************************
Removes a secondary index entry if possible. */
UNIV_INLINE
void row_purge_remove_sec_if_poss(
    /*=========================*/
    purge_node_t *node,  /* in: row purge node */
    dict_index_t *index, /* in: index */
    dtuple_t *entry)     /* in: index entry */
{
  ibool success;
  ulint n_tries = 0;

  /*	fputs("Purge: Removing secondary record\n", stderr); */

  success = row_purge_remove_sec_if_poss_low(node, index, entry, BTR_MODIFY_LEAF);
  if (success)
  {
    return;
  }
retry:
  success = row_purge_remove_sec_if_poss_low(node, index, entry, BTR_MODIFY_TREE);
  /* The delete operation may fail if we have little
  file space left: TODO: easiest to crash the database
  and restart with more file space */

  if (!success && n_tries < BTR_CUR_RETRY_DELETE_N_TIMES)
  {
    n_tries++;

    os_thread_sleep(BTR_CUR_RETRY_SLEEP_TIME);

    goto retry;
  }

  ut_a(success);
}

/***************************************************************
Purges a delete marking of a record. */
static void row_purge_del_mark(
    /*===============*/
    purge_node_t *node) /* in: row purge node */
{
  mem_heap_t *heap;
  dtuple_t *entry;
  dict_index_t *index;

  ut_ad(node);

  heap = mem_heap_create(1024);

  while (node->index != NULL)
  {
    index = node->index;

    /* Build the index entry */
    entry = row_build_index_entry(node->row, index, heap);

    row_purge_remove_sec_if_poss(node, index, entry);

    node->index = dict_table_get_next_index(node->index);
  }

  mem_heap_free(heap);

  row_purge_remove_clust_if_poss(node);
}

/***************************************************************
Purges an update of an existing record. Also purges an update of a delete
marked record if that record contained an externally stored field. */
static void row_purge_upd_exist_or_extern(
    /*==========================*/
    purge_node_t *node) /* in: row purge node */
{
  mem_heap_t *heap;
  dtuple_t *entry;
  dict_index_t *index;
  upd_field_t *ufield;
  ibool is_insert;
  ulint rseg_id;
  ulint page_no;
  ulint offset;
  ulint internal_offset;
  byte *data_field;
  ulint data_field_len;
  ulint i;
  mtr_t mtr;

  ut_ad(node);

  if (node->rec_type == TRX_UNDO_UPD_DEL_REC)
  {
    goto skip_secondaries;
  }

  heap = mem_heap_create(1024);

  while (node->index != NULL)
  {
    index = node->index;

    if (row_upd_changes_ord_field_binary(NULL, node->index, node->update))
    {
      /* Build the older version of the index entry */
      entry = row_build_index_entry(node->row, index, heap);

      row_purge_remove_sec_if_poss(node, index, entry);
    }

    node->index = dict_table_get_next_index(node->index);
  }

  mem_heap_free(heap);

skip_secondaries:
  /* Free possible externally stored fields */
  for (i = 0; i < upd_get_n_fields(node->update); i++)
  {
    ufield = upd_get_nth_field(node->update, i);

    if (ufield->extern_storage)
    {
      /* We use the fact that new_val points to
      node->undo_rec and get thus the offset of
      dfield data inside the unod record. Then we
      can calculate from node->roll_ptr the file
      address of the new_val data */

      internal_offset = ((byte *)ufield->new_val.data) - node->undo_rec;

      ut_a(internal_offset < UNIV_PAGE_SIZE);

      trx_undo_decode_roll_ptr(node->roll_ptr, &is_insert, &rseg_id, &page_no, &offset);
      mtr_start(&mtr);

      /* We have to acquire an X-latch to the clustered
      index tree */

      index = dict_table_get_first_index(node->table);

      mtr_x_lock(dict_tree_get_lock(index->tree), &mtr);

      /* NOTE: we must also acquire an X-latch to the
      root page of the tree. We will need it when we
      free pages from the tree. If the tree is of height 1,
      the tree X-latch does NOT protect the root page,
      because it is also a leaf page. Since we will have a
      latch on an undo log page, we would break the
      latching order if we would only later latch the
      root page of such a tree! */

      btr_root_get(index->tree, &mtr);

      /* We assume in purge of externally stored fields
      that the space id of the undo log record is 0! */

      data_field = buf_page_get(0, page_no, RW_X_LATCH, &mtr) + offset + internal_offset;

#ifdef UNIV_SYNC_DEBUG
      buf_page_dbg_add_level(buf_frame_align(data_field), SYNC_TRX_UNDO_PAGE);
#endif /* UNIV_SYNC_DEBUG */

      data_field_len = ufield->new_val.len;

      btr_free_externally_stored_field(index, data_field, data_field_len, FALSE, &mtr);
      mtr_commit(&mtr);
    }
  }
}

/***************************************************************
Parses the row reference and other info in a modify undo log record. */
static ibool row_purge_parse_undo_rec(
    /*=====================*/
    /* out: TRUE if purge operation required:
    NOTE that then the CALLER must unfreeze
    data dictionary! */
    purge_node_t *node, /* in: row undo node */
    ibool *updated_extern,
    /* out: TRUE if an externally stored field
    was updated */
    que_thr_t *thr) /* in: query thread */
{
  dict_index_t *clust_index;
  byte *ptr;
  trx_t *trx;
  dulint undo_no;
  dulint table_id;
  dulint trx_id;
  dulint roll_ptr;
  ulint info_bits;
  ulint type;
  ulint cmpl_info;

  ut_ad(node && thr);

  trx = thr_get_trx(thr);

  ptr = trx_undo_rec_get_pars(node->undo_rec, &type, &cmpl_info, updated_extern, &undo_no, &table_id);
  node->rec_type = type;

  if (type == TRX_UNDO_UPD_DEL_REC && !(*updated_extern))
  {
    return (FALSE);
  }

  ptr = trx_undo_update_rec_get_sys_cols(ptr, &trx_id, &roll_ptr, &info_bits);
  node->table = NULL;

  if (type == TRX_UNDO_UPD_EXIST_REC && cmpl_info & UPD_NODE_NO_ORD_CHANGE && !(*updated_extern))
  {
    /* Purge requires no changes to indexes: we may return */

    return (FALSE);
  }

  /* Prevent DROP TABLE etc. from running when we are doing the purge
  for this row */

  row_mysql_freeze_data_dictionary(trx);

  mutex_enter(&(dict_sys->mutex));

  node->table = dict_table_get_on_id_low(table_id, trx);

  mutex_exit(&(dict_sys->mutex));

  if (node->table == NULL)
  {
    /* The table has been dropped: no need to do purge */

    row_mysql_unfreeze_data_dictionary(trx);

    return (FALSE);
  }

  if (node->table->ibd_file_missing)
  {
    /* We skip purge of missing .ibd files */

    node->table = NULL;

    row_mysql_unfreeze_data_dictionary(trx);

    return (FALSE);
  }

  clust_index = dict_table_get_first_index(node->table);

  if (clust_index == NULL)
  {
    /* The table was corrupt in the data dictionary */

    row_mysql_unfreeze_data_dictionary(trx);

    return (FALSE);
  }

  ptr = trx_undo_rec_get_row_ref(ptr, clust_index, &(node->ref), node->heap);

  ptr = trx_undo_update_rec_get_update(ptr, clust_index, type, trx_id, roll_ptr, info_bits, trx, node->heap,
                                       &(node->update));

  /* Read to the partial row the fields that occur in indexes */

  if (!cmpl_info & UPD_NODE_NO_ORD_CHANGE)
  {
    ptr = trx_undo_rec_get_partial_row(ptr, clust_index, &(node->row), node->heap);
  }

  return (TRUE);
}

/***************************************************************
Fetches an undo log record and does the purge for the recorded operation.
If none left, or the current purge completed, returns the control to the
parent node, which is always a query thread node. */
static ulint row_purge(
    /*======*/
    /* out: DB_SUCCESS if operation successfully
    completed, else error code */
    purge_node_t *node, /* in: row purge node */
    que_thr_t *thr)     /* in: query thread */
{
  dulint roll_ptr;
  ibool purge_needed;
  ibool updated_extern;
  trx_t *trx;

  ut_ad(node && thr);

  trx = thr_get_trx(thr);

  node->undo_rec = trx_purge_fetch_next_rec(&roll_ptr, &(node->reservation), node->heap);
  if (!node->undo_rec)
  {
    /* Purge completed for this query thread */

    thr->run_node = que_node_get_parent(node);

    return (DB_SUCCESS);
  }

  node->roll_ptr = roll_ptr;

  if (node->undo_rec == &trx_purge_dummy_rec)
  {
    purge_needed = FALSE;
  }
  else
  {
    purge_needed = row_purge_parse_undo_rec(node, &updated_extern, thr);
    /* If purge_needed == TRUE, we must also remember to unfreeze
    data dictionary! */
  }

  if (purge_needed)
  {
    node->found_clust = FALSE;

    node->index = dict_table_get_next_index(dict_table_get_first_index(node->table));

    if (node->rec_type == TRX_UNDO_DEL_MARK_REC)
    {
      row_purge_del_mark(node);
    }
    else if (updated_extern || node->rec_type == TRX_UNDO_UPD_EXIST_REC)
    {
      row_purge_upd_exist_or_extern(node);
    }

    if (node->found_clust)
    {
      btr_pcur_close(&(node->pcur));
    }

    row_mysql_unfreeze_data_dictionary(trx);
  }

  /* Do some cleanup */
  trx_purge_rec_release(node->reservation);
  mem_heap_empty(node->heap);

  thr->run_node = node;

  return (DB_SUCCESS);
}

/***************************************************************
Does the purge operation for a single undo log record. This is a high-level
function used in an SQL execution graph. */

que_thr_t *row_purge_step(
    /*===========*/
    /* out: query thread to run next or NULL */
    que_thr_t *thr) /* in: query thread */
{
  purge_node_t *node;
  ulint err;

  ut_ad(thr);

  node = thr->run_node;

  ut_ad(que_node_get_type(node) == QUE_NODE_PURGE);

  err = row_purge(node, thr);

  ut_ad(err == DB_SUCCESS);

  return (thr);
}
